Is there any functionality within Arc Web Apps to click on a feature and have lines drawn to other features. I have a list of states and counts of how many people migrated to that state from other states. I would like to be able to click on a state (Florida) and have lines drawn from other states with larger lines representing larger migration counts.
No there is nothing already developed for this workflow. Developing a custom widget for this is the route you would want to go down. There are a lot of variables here.
As I mentioned it is possible but you would have to do the development.